The solution of this problem comes when one realizes that the marked spaces actually form a bulky five.
After , black has two secure eyes.
and
are added only to clarify the situation.
After , this area is only one eye. The marked space can also never be more than a false eye, so black is dead.
Doesn't black have still a ko if he plays under white 1 ?
unkx80: No. After , black dies with a straight three and the marked point is still a false eye.
White should not capture with here, because she can kill without ko.